
const fp = require('lodash/fp');
const cars = [
    {
        name: 'Ferrari FF', horsepower: 660, dollar_value: 700000, in_stock: true
    },
    {
        name: 'Spyker C12 Zagato', horsepower: 650, dollar_value: 648000, in_stock: false
    },
    {
        name: 'Jaguar XKR-S', horsepower: 550, dollar_value: 132000, in_stock: false
    },
    {
        name: 'Audi R8', horsepower: 525, dollar_value: 114200, in_stock: false
    },
    {
        name: 'Aston Martin One-77', horsepower: 750, dollar_value: 1850000, in_stock: true
    },
    {
        name: 'Pagani Huayra', horsepower: 700, dollar_value: 1300000, in_stock: false
    }
];

// 练习1 使用函数组合fp.flowRight实现获取数组最后一项的in_stock属性值
const isLastInStock = fp.flowRight(fp.prop("in_stock"), fp.last);
console.log(isLastInStock(cars));

// 练习2 使用函数组合获取第一个car的name
const firstCarName = fp.flowRight(fp.prop('name'), fp.first);
console.log(firstCarName(cars));

// 练习3 计算平均价格
let _average = function(xs) {
    return fp.reduce(fp.add, 0, xs) / xs.length;
}
let averageDollarValue = fp.flowRight(_average, fp.map(car=>car.dollar_value));
console.log(averageDollarValue(cars));

// 练习4 
let _underscore = fp.replace(/\W+/g, '_');
const sanitizeNames = fp.map(fp.flowRight(fp.toLower, _underscore, fp.prop('name')));
console.log(sanitizeNames(cars));
